win: wmain(): locale-independent argv (#7180)

fix #7060

src/nvim/CMakeLists.txt

@@ -10,6 +10,11 @@ if(USE_GCOV)
 endif()
 endif()
 
+if(WIN32)
+  # tell MinGW compiler to enable wmain
+  set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -municode")
+endif()
+
 set(TOUCHES_DIR ${PROJECT_BINARY_DIR}/touches)
 set(GENERATOR_DIR ${CMAKE_CURRENT_LIST_DIR}/generators)
 set(GENERATED_DIR ${PROJECT_BINARY_DIR}/src/nvim/auto)

src/nvim/main.c

@@ -7,6 +7,11 @@
 #include <string.h>
 #include <stdbool.h>
 
+#ifdef WIN32
+# include <wchar.h>
+# include <winnls.h>
+#endif
+
 #include <msgpack.h>
 
 #include "nvim/ascii.h"
@@ -215,10 +220,28 @@ void early_init(void)
 
 #ifdef MAKE_LIB
 int nvim_main(int argc, char **argv)
+#elif defined WIN32
+// don't use codepage encoded arguments. see #7060
+int wmain(int argc, wchar_t **argv_w)
 #else
 int main(int argc, char **argv)
 #endif
 {
+#ifdef WIN32
+  char *argv[argc];
+
+  for (size_t i = 0; i < (size_t)argc; i++) {
+    // get required buffer size
+    size_t dest_size = (size_t)WideCharToMultiByte(
+        CP_UTF8, 0, argv_w[i], -1, NULL, 0, NULL, NULL);
+    char *buf = (char *)xmallocz(dest_size);
+    // convert from utf16 (widechar) utf8 (multibyte)
+    WideCharToMultiByte(CP_UTF8, 0, argv_w[i], -1, buf, (int)dest_size,
+                        NULL, NULL);
+    argv[i] = buf;
+  }
+#endif
+
   argv0 = argv[0];
 
   char_u *fname = NULL;   // file name from command line